Nonimaging optical design breaking the conventional symmetry of headlamp optics by side lighting with white LEDs

This work proposes a novel design in which an LED is mounted on the side wall of a multi-segment reflector, breaking the conventional symmetry of headlamp optics for the application of vehicle such as bicycle where the headlamp is always requested compact and light. Monte Carlo ray tracing was used to optimize the reflector, which was divided into 16 segments to generate a hot spot for the cut-off line. A cylindrical lens array (CLA) was then introduced to laterally spread and homogenize the pattern, ensuring symmetry and uniformity. A CNC-machined aluminum mockup with 80% reflectivity was fabricated and tested using an automated measurement system at 10 m. The measured illumination patterns of both low and high beams were symmetrical and met all regulatory checkpoints. The results demonstrate the feasibility of side-mounted LEDs with segmented reflectors and CLAs for compact bicycle headlamp designs.